Video display system and video display method

ABSTRACT

A video display system includes: a tone mapping processor; a display; and a metadata processor that generates first dynamic metadata that indicates a maximum luminance that is constant over a plurality of time intervals by using static metadata. The video display system switches between: a first operation of (i) generating the first dynamic metadata by using the static metadata, performed by the metadata processor and (ii) performing the tone mapping process by using the first dynamic metadata, performed by the tone mapping processor; and a second operation of performing the tone mapping process by using second dynamic metadata in which the maximum luminance varies over the plurality of time intervals, performed by the tone mapping processor.

CROSS-REFERENCE OF RELATED APPLICATIONS

This application is the U.S. National Phase under 35 U.S.C. § 371 ofInternational Patent Application No. PCT/JP2018/006862, filed on Feb.26, 2018, which in turn claims the benefit of U.S. ProvisionalApplication No. 62/569,301, filed on Oct. 6, 2017, the entiredisclosures of which Applications are incorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates to a video display system and a videodisplay method for displaying a video.

BACKGROUND ART

Patent Literature (PTL) 1 discloses a method and a system for mappinggraphics on an image of an HDR (High Dynamic Range) video.

CITATION LIST Patent Literature

-   PTL 1: Japanese Patent No. 6104411

Non-Patent Literature

-   NPL 1: White Paper Blu-ray Disc Read-Only Format (Ultra HD Blu-ray),    Audio Visual Application Format Specifications for BD-ROM Version    3.1, August 2016,    http://www.blu-raydisc.com/Assets/Downloadablefile/BD-ROM_Part3_V3.1_WhitePa    per_160729_clean.pdf

SUMMARY OF THE INVENTION Technical Problem

The present disclosure provides a video display system and a videodisplay method that can improve the quality of a video displayed.

Solution to Problem

A video display system according to an aspect of the present disclosureincludes: a tone mapping processor that performs a tone mapping processof, by using dynamic metadata indicating a maximum luminance of a videoin each of a plurality of time intervals included in a predeterminedperiod, converting a luminance of the video in each time interval basedon conversion characteristics according to the maximum luminance of thevideo in the time interval; a display that displays the video that hasundergone the tone mapping process; and a metadata processor thatgenerates first dynamic metadata that indicates the maximum luminancethat is constant over the plurality of time intervals by using staticmetadata that indicates a maximum luminance of the video in thepredetermined period. The video display system switches between: a firstoperation of (i) generating the first dynamic metadata by using thestatic metadata, performed by the metadata processor, and (ii)performing the tone mapping process by using the first dynamic metadata,performed by the tone mapping processor; and a second operation of thetone mapping processor performing the tone mapping process by usingsecond dynamic metadata in which the maximum luminance varies over theplurality of time intervals.

Advantageous Effect of Invention

The present disclosure can provide a video display system and a videodisplay method that can improve the quality of a video displayed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating the evolution of imaging technology.

FIG. 2 is a diagram illustrating the relationship between videoproduction, delivery methods, and display apparatuses when a new videorepresentation is introduced into content.

FIG. 3A is a diagram showing an example of tone mapping.

FIG. 3B is a diagram showing an example of tone mapping.

FIG. 4A is a diagram showing an example of static tone mapping.

FIG. 4B is a diagram showing an example of dynamic tone mapping.

FIG. 5 is a diagram showing an example in which graphics are overlaid ona moving image, and the resulting moving image is displayed.

FIG. 6 is a diagram showing a configuration of a conventional videodisplay system.

FIG. 7 is a diagram showing a configuration of a conventional videodisplay system.

FIG. 8 is a diagram showing the influence of dynamic tone mapping whengraphics are overlaid on a main video.

FIG. 9 is a diagram showing a configuration of a video display systemaccording to an embodiment.

FIG. 10 is a diagram showing the relationship between various types offlags and the operations of a video display apparatus according to theembodiment.

FIG. 11 is a diagram showing a configuration of the video displayapparatus according to the embodiment.

FIG. 12 is a diagram showing a configuration of a metadata processoraccording to the embodiment.

FIG. 13 is a flowchart illustrating the operations of a videoreproduction apparatus according to the embodiment.

FIG. 14 is a flowchart illustrating the operations of the video displayapparatus according to the embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

[1-1. Background]

First, the transition of imaging technology will be described withreference to FIG. 1. FIG. 1 is a diagram illustrating the evolution ofimaging technology.

In order to enhance video image quality, conventionally, the focus hasbeen given to increase the number of pixels displayed. Accordingly,standard definition (SD) videos (720×480 pixels) and high definition(HD) videos (1920×1080 pixels) are now widely used.

In recent years, in order to achieve even higher image quality,introduction of ultra-high definition (UHD) videos (3840×1920 pixels),or so-called 4K resolution videos (with a 4K resolution of 4096×2048pixels) has started.

Along with the introduction of 4K resolution videos, consideration isalso given to expanding the dynamic range, expanding the color gamut,adding or improving the frame rate, and the like.

Among these, with respect to the dynamic range, HDR (High Dynamic Range)rendering is receiving increased attention as a method for representingbright light, such as specular reflection light, that cannot berepresented by a currently used television signal to be more close toreality while maintaining low light signal gradation. Specifically,conventional television signals are called SDR (Standard Dynamic Range)signals, and the highest luminance is 100 nits. In contrast, in HDRsignals, the highest luminance is expected to be up to 1000 nits ormore. For HDR signals, standardization of mastering display standards iscurrently undertaken by SMPTE (Society of Motion Picture & TelevisionEngineers), ITU-R (International Telecommunications Union Radiocommunications Sector), and the like.

Specific applications of HDR include, as with HD and UHD, broadcasting,packaged media (Blu-ray® disc, and the like), internet delivery, and thelike.

[1-2. Relationship between Generation of Master, Delivery Methods, andDisplay Apparatuses]

FIG. 2 is a diagram illustrating the relationship between videoproduction, delivery methods, and display apparatuses when a new videorepresentation is introduced into content.

In the case where a new video representation is introduced (for example,the number of pixels is increased) so as to enhance video image quality,as shown in FIG. 2, it is necessary to (1) change a master for homeentertainment on the video production side. Along with this change, itis also necessary to (2) update the delivery method such asbroadcasting, communication, or a packaged medium, and also (3) updatethe display apparatus such as a television set or a projector fordisplaying the video.

[1-3. Tone Mapping]

Tone mapping is processing for adjusting, based on the relationshipbetween the luminance of an HDR video and the maximum luminance (DisplayPeak Luminance: DPL) of a video display apparatus, the luminance of thevideo to be less than or equal to DPL by converting the luminance of thevideo if the maximum luminance (Maximum Content Luminance Level: MaxCLL)of the video exceeds DPL. Through this processing, the video can bedisplayed without losing information near the maximum luminance of thevideo. The conversion depends on the characteristics of the videodisplay apparatus, and also depends on how to display the video, andthus different conversion characteristics are used for each videodisplay apparatus.

FIGS. 3A and 3B are diagrams showing examples of tone mapping. FIG. 3Ashows a case where DPL is 500 nits, and FIG. 3B shows a case where DPLis 1000 nits. Also, FIGS. 3A and 3B each show an example of tone mappingperformed when a video having a MaxCLL of 1000 nits is displayed and anexample of tone mapping performed when a video having a MaxCLL of 4000nits is displayed.

As shown in FIG. 3A, in the case where DPL is 500 nits, in both videos,the luminance is converted such that the video can be displayed at up toMaxCLL below 500 nits, but the degree of conversion is higher in thevideo having a higher MaxCLL.

As shown in FIG. 3B, in the case where DPL is 1000 nits, in the videohaving a MaxCLL of 1000 nits, tone mapping is not performed. In thevideo having a MaxCLL of 4000 nits, tone mapping is performed so as toconvert the luminance from 4000 nits to 1000 nits, and the video isdisplayed at that luminance.

[1-4. Dynamic Metadata and Dynamic Tone Mapping]

FIG. 4A is a diagram showing an example of tone mapping using staticmetadata. FIG. 4B is a diagram showing an example of dynamic tonemapping using dynamic metadata.

As shown in FIG. 4A, in the case where static metadata (MaxCLL) is used,MaxCLL indicates the highest luminance in a video sequence, and thus thevideo display apparatus can perform only fixed tone mapping on the videosequence. In contrast, as shown in (a) in FIG. 4B, in the case wheremetadata suitable according to the luminance that varies with time(here, referred to as Dynamic MaxCLL) is used, the video displayapparatus does not perform tone mapping when the luminance is low ((b)in FIG. 4B), and performs tone mapping when the luminance is high ((c)in FIG. 4B). In this way, optimal tone mapping suitable for theluminance that varies with time can be implemented.

[1-5. Overlaying Graphics on Video]

FIG. 5 is a diagram showing an example in which graphics such as a menuand subtitles are overlaid on a moving image, and the moving image isdisplayed on a video display apparatus. Here, an example of Ultra HDBlu-ray is shown.

A set of moving images before graphics are overlaid will be referred toas a main video. With Ultra HD Blu-ray, graphics are prepared in HDresolution. A video reproduction apparatus performs HD-UHD conversion onthe graphics in HD resolution so as to generate graphics in UHDresolution. Then, the video reproduction apparatus overlays the obtainedgraphics in UHD resolution with the main video having UHD resolution.Then, the video reproduction apparatus transmits the video resultingfrom the overlay process to a video display apparatus via HDMI®(High-Definition Multimedia Interface). The video display apparatusdisplays the transmitted video in HDR.

Also, the video reproduction apparatus determines dynamic metadata basedon the variation of the luminance of the main video with time, andtransmits the dynamic metadata to the video display apparatus via HDMI.The video display apparatus performs dynamic tone mapping on a videosignal of the video obtained by overlaying subtitles and menus on themain video based on the transmitted dynamic metadata.

The same applies to an HDR video that is displayed through an OTT (overthe top) service via broadcasting or communication and in which a menuor subtitles are overlaid on a main video, and the resulting video isdisplayed on a video display apparatus.

[1-6. Conventional Video Reproduction Apparatus]

A configuration of a conventional HDR-compatible video reproductionapparatus will be described. First, a video reproduction apparatus thatsupports only static metadata (HDR10, in the case of Mandatory HDRspecified by BDA) will be described.

FIG. 6 is a diagram showing a configuration of conventional videodisplay system 100. Video display system 100 includes video reproductionapparatus 101 and video display apparatus 102. Video reproductionapparatus 101 is an HDR-compatible video reproduction apparatus, andincludes disc 111, BD-ROM driver 112, demultiplexer 113, PG decoder (PGDec) 114, video decoder (Video Dec) 115, menu controller 116, staticmetadata extractor 117, video composer 118, and video informationoutputter 119.

Disc 111 is a recording medium such as, for example, a BD-ROM media discin which a video and other necessary information are recorded. BD-ROMdriver 112 reads information from disc 111. Demultiplexer 113 extractssubtitles information, video information, and audio information (notshown) from the information output from BD-ROM driver 112.

PG decoder 114 generates subtitle graphics from the subtitlesinformation extracted by demultiplexer 113. Video decoder 115 generatesa video signal from the video information extracted by demultiplexer113.

Menu controller 116 performs generation of menu graphics and controlthereof by using the information output from BD-ROM driver 112. Staticmetadata extractor 117 extracts static metadata from the informationoutput from BD-ROM driver 112.

Video composer 118 generates a video signal by overlaying the menugraphics generated by menu controller 116, the subtitle graphicsgenerated by PG decoder 114, and the video information generated byvideo decoder 115. Video information outputter 119 transmits the videosignal generated by video composer 118, the audio signal (not shown)extracted by demultiplexer 113, and the static metadata extracted bystatic metadata extractor 117 to video display apparatus 102 via atransmitter such as HDMI.

Next, a configuration of an HDR-compatible video reproduction apparatushaving dynamic metadata will be described. FIG. 7 is a diagram showing aconfiguration of video display system 100A that includes HDR-compatiblevideo reproduction apparatus 101A having dynamic metadata. Video displaysystem 100 includes video reproduction apparatus 101A and video displayapparatus 102A.

Video reproduction apparatus 101A includes, in addition to thestructural elements of video reproduction apparatus 101 shown in FIG. 6,dynamic metadata extractor 120 and metadata switch 121.

Dynamic metadata extractor 120 extracts dynamic metadata included in thevideo information generated by video decoder 115. Metadata switch 121performs processing such as switching the metadata to be output betweenthe dynamic metadata extracted by dynamic metadata extractor 120 and thestatic metadata extracted by static metadata extractor 117, oroutputting both metadata. Video information outputter 119 transmits themetadata output from metadata switch 121 together with the video signalto video display apparatus 102A via a transmitter such as HDMI.

Here, an example has been described in which the dynamic metadata isincluded in the video information, but the dynamic metadata may berecorded in disc 111 separately, and transmitted to metadata switch 121in synchronization with the video information. With this configuration,dynamic tone mapping based on the dynamic metadata can be implemented byvideo display apparatus 102.

The details of Blu-ray and Ultra HD Blu-ray are disclosed in, forexample, Non-Patent Literature (NPL) 1.

[1-7. Problem Arising when Performing Dynamic Tone Mapping on Video Datawhere Graphics are Overlaid on Moving Image]

In the dynamic metadata method, metadata regarding the luminance of theHDR video such as luminance distribution is designated for each frame,and the metadata is transmitted to the video display apparatus togetherwith the video signal. The video display apparatus performs processingsuch as luminance conversion based on the transmitted metadata accordingto the display capabilities of the video display apparatus such asmaximum luminance. The dynamic metadata method as described above isreceiving increased attention as a method for displaying a video at aconstant quality as much as possible irrespective of the displayperformance of a video display apparatus such as luminance.

However, dynamic metadata varies with time, and thus there is a problemin that a video that needs to be displayed stably is not displayedstably.

If the video to be displayed is a video or a set of so-called movingimages that is simultaneously edited or supervised, processing can beperformed considering the state of the video to some degree. Whengraphics data such as subtitles or a menu whose luminance is essentiallyconstant and does not vary at all is overlaid on a main video composedof a set of moving images as described above and displayed, due to theprocessing that uses dynamic metadata, a negative effect occurs such asvariation of the luminance or color of the graphics that essentiallyneeds to be constant. This negative effect becomes more prominent as theluminance of the main video is higher and the luminance of the videodisplay apparatus is lower.

FIG. 8 is a diagram showing the influence of dynamic tone mapping whengraphics are overlaid on a main video. It is assumed here that, as shownin (a) in FIG. 8, graphics to be overlaid has a luminance of 350 nits.As shown in (b) in FIG. 8, in a section in which the luminance of themain video is low, tone mapping is not performed, and thus the graphicsare displayed on a video display apparatus at a luminance of 350 nitsthat is the original luminance of the graphics. On the other hand, asshown in (c) in FIG. 8, in a section in which the luminance of the mainvideo is high, tone mapping is performed, and thus the graphics aredisplayed on the video display apparatus at a luminance lower than 350nits. In this way, the graphics luminance that essentially needs to beconstant varies with time, resulting in an undesired state. In thisexample, only the influence on the luminance is considered, but in anactual video display apparatus, the influence may also be exerted oncolor components, and thus colors may also be affected.

[1-8. Solution]

As a means for avoiding the problem described above, a method may beconceived in which the position information of graphics to be overlaidis transmitted to the video display apparatus, and dynamic metadata isnot used in an area where the graphics are displayed. However, it isvery difficult to implement this method because it is necessary totransmit information that indicates whether graphics are displayed inthe entire region of the display screen, and also necessary to makedeterminations for each display pixel in the processing performed by thevideo display apparatus.

Also, as described above, when the video reproduction apparatustransmits additional information for causing the video display apparatusto perform the right processing to the video display apparatus, and thevideo display apparatus performs processing for displaying the HDR videoon which graphics have been overlaid, the way the video looks may varydepending on the implementation on the video display apparatus side.This is recognized as a serious problem by content creators. For thisreason, in order to constantly perform the right processing, the videoreproduction apparatus performs processing according to thespecifications in which the operations of the video reproductionapparatus are defined such as Blu-ray specifications so as to processdynamic metadata to be transmitted to the video display apparatus. Withthis configuration, the video display apparatus can display the videoappropriately. However, an image quality degradation may occur dependingon the processing on the video display apparatus side, and thus a methodincluding processing on the video display apparatus side is needed.

In the present disclosure, the following solutions are used. At the timeof reproduction of the HDR video, a flag (Graphics_Menu_On_Flag: GMOF)indicating whether a menu is overlaid and displayed is set wherenecessary when menu graphics are displayed. In the case of a Blu-raydisc, this setting is performed by an HDMV (High Definition Movie Mode)command or a BD-J (Blu-ray Disc Java®) command.

In the case where a disc on which HDR video data or the like isrecorded, or HDR data is reproduced, when graphics such as a menu isoverlaid and displayed on the HDR video, the video reproductionapparatus sets the GMOF flag to ON. Also, the video reproductionapparatus does not transmit the GMOF flag to the video display apparatuswhen a tone mapping process or graphics conversion is performed on thevideo reproduction apparatus side.

When a tone mapping process is performed by the video display apparatus,the video reproduction apparatus transmits a value corresponding tostatic metadata to the video display apparatus as dynamic metadata. As aresult, the video display apparatus fixes the tone mapping, and it istherefore possible to reduce the influence on the graphics.

When the video reproduction apparatus changes the dynamic metadata to avalue corresponding to static metadata, or changes the valuecorresponding to static metadata back to the original dynamic metadata,the video reproduction apparatus gradually changes the value of metadataso as to perform a smooth transition. Accordingly, it is possible toreduce the sense of discomfort in the variation of tone mapping due tothe metadata being changed.

In the case where the maximum luminance (MaxLLGM) of menu graphics isdesignated on the disc or HDR data, the video reproduction apparatusacquires MaxLLGM. Alternatively, the video reproduction apparatusgenerates a value corresponding to MaxLLGM by analyzing the menugraphics. Also, the video reproduction apparatus receives, from thevideo display apparatus, the maximum luminance information (MAXTVLL) ofthe display apparatus. Then, the video reproduction apparatus comparesMaxLLGM and MAXTVLL, and determines whether there is an influence ofdynamic tone mapping on the menu graphics. If it is determined thatthere is no influence, the video reproduction apparatus does not performdynamic metadata conversion processing even when the GMOF flag is set toON. Accordingly, it is possible to make tone mapping as dynamic aspossible on the video display apparatus side, and thus implement bettervideo display.

When GMOF is transmitted to the video display apparatus, the videodisplay apparatus can recognize the fact that graphics are overlaid onthe HDR video, and thus perform an appropriate tone mapping process.That is, the video display apparatus switches the processing to, forexample, processing of performing tone mapping according to the dynamicmetadata, processing of fixing the tone mapping is fixed, processing ofperforming tone mapping according to the static metadata, or processingof combining the above processing operations according to the luminancelevel, based on the luminance level of the video display apparatus (forexample, a TV set), the luminance level of the content, and theluminance level (MaxLLGM) of the graphics. With this configuration, thevideo display apparatus can perform appropriate processing.

At this time, the video display apparatus can perform more appropriateprocessing by using, in the tone mapping process, the maximum luminance(MaxLLGM) of menu graphics designated in the disc or the HDR data, orMaxLLGM generated inside the video reproduction apparatus.

Also, when GMOF is set to ON, the video reproduction apparatus sets aTV-side processing priority flag (TVPAF). When TVPAF is set to ON, thevideo reproduction apparatus sets the Dynamic Metadata Block Mode Flag(DMBM) to OFF, and transmits DMBM to the video display apparatus. Inthis case, appropriate processing according to the luminance of thevideo display apparatus is allowed.

When TVPAF is set to OFF, the video reproduction apparatus sets DMBM toON, and transmits DMBM to the video display apparatus. In this case, thevideo display apparatus is forced to perform processing according to thedynamic metadata. That is, the video display apparatus performsprocessing according to the dynamic metadata processed on the videoreproduction apparatus side. Accordingly, processing on the dynamicmetadata in the video reproduction apparatus is clearly designated, thevideo can be displayed in a similar manner by most video displayapparatuses.

With the method described above, the influence of dynamic tone mappingon graphics such as menus or subtitles can be reduced when dynamic tonemapping is performed on an HDR video signal transmitted viabroadcasting, a packaged medium such as a Blu-ray disc, or internetdelivery such as OTT. As a result, it is possible to obtain advantageouseffects of stable graphics display and dynamic tone mapping according tothe maximum luminance (DPL) of the video display apparatus and themaximum luminance of the moving images.

With the description above, in particular, in the case where theluminance of the video display apparatus is lower than the luminance ofa video, HDR effects can be increased, and menus and subtitles can bedisplayed with high quality as high as that of static tone mapping.

Furthermore, by the video reproduction apparatus transmitting dynamicmetadata corresponding to static tone mapping that is not dependent onthe processing on the video display apparatus such as a TV set to thevideo display apparatus, an intention of the content creator can bereproduced more faithfully. On the other hand, if the content creatorallows, processing on the video display apparatus side may be selected.Accordingly, by selecting appropriate processing according to the stateof graphics, it is possible to suppress the influence on graphics whilemaximizing the advantageous effects of dynamic tone mapping.

[2-1. Configuration of Video Display System]

FIG. 9 is a diagram showing a configuration of video display system 100Baccording to the present embodiment. Video display system 100B includesvideo reproduction apparatus 101B and video display apparatus 102B.

Video reproduction apparatus 101B includes disc 111, BD-ROM driver 112,demultiplexer 113, PG decoder (PG Dec) 114, video decoder (Video Dec)115, menu controller 116B, static metadata extractor 117, video composer118, video information outputter 119, dynamic metadata extractor 120,and metadata processor 122.

Disc 111 is a recording medium such as, for example, a BD-ROM mediadisc, in which a video and other necessary information are recorded.BD-ROM driver 112 reads information from disc 111. Demultiplexer 113extracts subtitles information, video information, and audio information(not shown) from the information output from BD-ROM driver 112.

PG decoder 114 generates subtitle graphics from the subtitlesinformation extracted by demultiplexer 113. Video decoder 115 generatesa video signal from the video information extracted by demultiplexer113.

Menu controller 116B performs generation of menu graphics and controlthereof by using the information output from BD-ROM driver 112. Also,menu controller 116B outputs menu graphics state information (GMOF,TVPAF, and MaxLLGM) to metadata processor 122.

Static metadata extractor 117 extracts static metadata from theinformation output from BD-ROM driver 112. The static metadata includesinformation indicating video luminance (for example, maximum luminanceand average luminance). The video luminance indicated by the staticmetadata is video luminance (fixed value) in a predetermined period.

Video composer 118 generates a video signal by overlaying the menugraphics generated by menu controller 116B, the subtitle graphicsgenerated by PG decoder 114, and the video information generated byvideo decoder 115. That is, video composer 118 overlays the menugraphics and the subtitle graphics on the video information.

Dynamic metadata extractor 120 extracts the dynamic metadata from thevideo information generated by video decoder 115. The dynamic metadatamay be recorded in disc 111 separately, and transmitted to metadataprocessor 122 in synchronization with the video information. Also, thedynamic metadata includes information that indicates the luminance (forexample, maximum luminance and average luminance) of the video. Theluminance of the video indicated by the dynamic metadata chronologicallyvaries during a predetermined period. That is, the dynamic metadataindicates the maximum luminance of the video in each of a plurality oftime intervals included in the predetermined period of the staticmetadata.

Metadata processor 122 processes the dynamic metadata extracted bydynamic metadata extractor 120 and the static metadata extracted bystatic metadata extractor 117 by using the menu graphics stateinformation output from menu controller 116B and the luminanceinformation (MAXTVLL) of video display apparatus 102B, and changes thedynamic metadata according to the state of menu graphics. Also, metadataprocessor 122 acquires MAXTVLL from, for example, video displayapparatus 102B as EDID.

Video information outputter 119 transmits the video signal generated byvideo composer 118, the audio signal (not shown) extracted bydemultiplexer 113, and the dynamic metadata and the static metadataprocessed by metadata processor 122 to video display apparatus 102B viaa transmitter such as HDMI.

Menu controller 116B is implemented by, for example, a BD-J engine thatprocesses a Java command such as BD-J, or an HDMV command interpreterthat processes an HDMV command written in the stream as IG.

[2-2. Flag and State]

Hereinafter, each flag and its state will be described in detail.Graphics_Menu_On_Flag (GMOF) is a flag indicating whether menu graphicsare overlaid and displayed at the time of reproduction of the HDR video.GMOF is set with a BD-J command or an HDMV command. Even when menugraphics are displayed, GMOF is set to OFF if the menu graphics are notaffected by dynamic tone mapping such as when the menu graphics aretransparent, when the display region on which the menu graphics aredisplayed is small, or when the luminance of the menu graphics issufficiently low.

GMOF=OFF indicates that menu graphics are not overlaid or menu graphicsfor which the influence of dynamic tone mapping needs not be consideredare displayed at the time of reproduction of the HDR video.

GMOF=ON indicates that menu graphics that may be affected by theinfluence of dynamic tone mapping are overlaid at the time ofreproduction of the HDR video. That is, GMOF=ON indicates that thecontent creator intends to reduce the influence of dynamic tone mappingon the menu graphics by performing some kind of processing in the videoreproduction apparatus or the video display apparatus.

Maximum_Luminance_Level_of_Graphics_Menu (MaxLLGM) indicates the maximumluminance of the menu graphics. MaxLLGM is set as a parameter of GMOF.Accordingly, when GMOF is turned off, MaxLLGM is not set.

MaxLLGM=0 indicates that the maximum luminance of the menu graphics isnot known, or the menu graphics are transparent.

MaxLLGM=1 to the maximum value indicates the maximum luminance of themenu graphics. The maximum value is arbitrarily defined. For example, inthe case where the maximum value is set to 1000 nits, which is themaximum luminance of normally used mastering monitors, when MaxLLGM isset to 8 bits, the maximum luminance of the menu graphics is indicatedwith an increment of about 4 nits. When MaxLLGM is set to 10 bits, themaximum luminance of the menu graphics is indicated with an increment ofabout 1 nit.

Maximum_TV_Luminance_Level (MAXTVLL) indicates the maximum luminance atwhich the video display apparatus can display. Video reproductionapparatus 101B acquires MAXTVLL from, for example, video displayapparatus 102B as EDID. Alternatively, the user may set MAXTVLL as theinitial settings in video reproduction apparatus 101B.

MAXTVLL may indicate a specific luminance value, or a luminance range towhich the maximum luminance of the video display apparatus belongs. Thatis, any one of the plurality of formats described below can be used forMAXTVLL.

MAXTVLL=0 indicates that the maximum luminance of the video displayapparatus is not known. MAXTVLL=1 to the maximum value indicates aspecific maximum luminance value of the video reproduction apparatus. Inthis case, for example, as with MAXLLG, the increment is determinedbased on the maximum luminance and the bit number. For example, when themaximum value is set to 1000 nits, and display is shown with 8 bits, themaximum luminance of the video reproduction apparatus is indicated by anincrement of 4 nits.

Alternatively, MAXTVLL may indicate a luminance range. In this case, forexample, MAXTVLL indicates the center value of the luminance range. Forexample, in the case where the maximum value is 1000 nits, MAXTVLLindicates any one of 1000 nits, 500 nits, and 200 nits. When MAXTVLL is1000 nits, it indicates that the maximum luminance of the video displayapparatus is 700 nits or more. When MAXTVLL is 500 nits, it indicatesthat the maximum luminance of the video display apparatus is included ina luminance range of 300 nits to 800 nits. When MAXTVLL is 200 nits, itindicates that the maximum luminance of the video display apparatus is400 nits or less. As described above, the luminance range may or may notbe defined in an overlapping manner. Also, MAXTVLL may indicate an indexor the like assigned to the luminance range instead of indicating aluminance value such as the center value. For example, with MAXTVLL=1, aluminance range of 400 nits or less is shown. With MAXTVLL=2, aluminance range of 300 to 800 nits is shown, and with MAXTVLL=3, aluminance range of 700 nits or more is shown.

TV Processing Authorized Flag (TVPAF) is a flat indicating whether ornot to prioritize the processing of the video display apparatus, andindicates whether the video display apparatus is allowed to processmetadata.

TVPAF is set as a parameter of GMOF. Accordingly, when GMOF is set toOFF, TVPAF is not set.

TVPAF=OFF indicates that processing in the video display apparatus isnot allowed. That is, this means that dynamic metadata is set to anappropriate value in the video reproduction apparatus.

TVPAF=ON indicates that the processing in the video display apparatus isprioritized. That is, the video reproduction outputs the dynamicmetadata and the static metadata recorded in the HDR video withoutchanging the dynamic metadata and the static metadata.

Dynamic Metadata Block Mode Flag (DMBM) indicates whether it isnecessary to process the dynamic metadata in the video displayapparatus. DMBM is a flag transmitted from the video reproductionapparatus to the video display apparatus together with the metadata.

DMBM=OFF indicates that the dynamic metadata can be changed by the videodisplay apparatus. That is, in this case, when GMOF=ON, the videodisplay apparatus can perform tone mapping using the static metadatainstead of the dynamic metadata, or processing according to thecharacteristics of the video display apparatus by analyzing the HDRvideo data.

DMBM=ON indicates that the video display apparatus is required toperform processing according to the dynamic metadata transmitted fromthe video reproduction apparatus.

FIG. 10 is a diagram showing the relationship between combinations ofthese values and the tone mapping process performed in the video displayapparatus.

Mode 0 indicates that no menu graphics overlaid, and dynamic tonemapping is performed according to the dynamic metadata. Mode 1 indicatesthat menu graphics are overlaid, but the video display apparatus selectsappropriate tone mapping. Mode 2 indicates that menu graphics areoverlaid, but the video reproduction apparatus determines that there isno influence of dynamic tone mapping on the menu graphics, and the videodisplay apparatus performs dynamic tone mapping according to the dynamicmetadata. Mode 3 indicates that the video reproduction apparatusdetermines that there is an influence of dynamic tone mapping on themenu graphics, and sets dynamic metadata corresponding to staticmetadata as the dynamic metadata to be transmitted to the video displayapparatus so as to fix tone mapping, and static tone mapping isperformed.

First, in the case where Java API (application programing interface) orHDMV IG is invoked, in Mode 1, the video display apparatus (for example,a TV set) is allowed to perform additional processing by the studio(content creator), and thus TVPAF=ON (1) is set.

The video reproduction apparatus transmits GMOF=1 (ON), DMBM)=0 (OFF)and MaxLLGM to the video display apparatus via HDMI VSIF (VendorSpecific InfoFrame). In this case, the video display apparatus (TV set)may change the tone mapping curve of the video display apparatus so asto not affect MaxLLGM, and maintain the dynamic metadata mode (dynamictone mapping).

In Mode 2, the video display apparatus (for example, a TV set) is notallowed to perform additional processing by the studio (contentcreator), and thus TVPAF=OFF (0) is set. Also, it is determined by theHDR10+ algorithm that MAXTVLL is sufficiently high, or MaxLLGM issufficiently lower than MAXTVLL. In this case, operations similar tothose of Mode 1 are performed.

In Mode 3, TVPAF=OFF (0), and it is determined by the HDR10+ algorithmthat MaxLLGM is not sufficiently lower than MAXTVLL.

In this case, the video reproduction apparatus transmits GMOF=1 (ON),DMBM=1 (ON), and MaxLLGM to the video display apparatus via HDMI VSIF.Also, the dynamic metadata in VSIF is set to a fixed static value. Also,the video reproduction apparatus has, as an option, a function ofgradually changing the value of metadata.

[2-3. Configuration of Video Display Apparatus]

FIG. 11 is a block diagram showing a configuration of video displayapparatus 102B according to the present embodiment. Video displayapparatus 102B includes luminance information storage 131, videoreceiver 132, metadata acquirer 133, tone mapping processor 134, anddisplay 135.

A video signal, dynamic metadata, and static metadata are input fromvideo reproduction apparatus 101B to video display apparatus 102B via avideo information transmitter such as HDMI. Also, video displayapparatus 102B transmits information indicating the capabilities ofvideo display apparatus 102B to video reproduction apparatus 101B asEDID.

Luminance information storage 131 stores maximum luminance information(MAXTVLL) for displaying images. Video display apparatus 102B transmitsMAXTVLL to video reproduction apparatus 101B via EDID. At this time,video display apparatus 102B simultaneously transmits, to videoreproduction apparatus 101B, information indicating that video displayapparatus 102B supports specify dynamic metadata and is capable ofperforming a dynamic tone mapping process.

Video receiver 132 receives the video signal and the metadata. Videoreceiver 132 transmits the video signal to tone mapping processor 134,and the metadata to metadata acquirer 133. Metadata acquirer 133acquires various types of parameters of the dynamic metadata includinginformation such as GMOF, MaxLLGM, and DMBM, and various types ofparameters of the static metadata, and transmits the acquired parametersto tone mapping processor 134.

Tone mapping processor 134 performs an appropriate tone mapping processon the input video signal by using MAXTVLL, the attribute of display135, and the metadata transmitted from metadata acquirer 133, andoutputs the processed video signal to display 135. Display 135 displaysa video based on the processed video signal.

[2-4. Configuration of Metadata Processor]

FIG. 12 is a block diagram showing a configuration of metadata processor122 included in video reproduction apparatus 101B according to thepresent embodiment. Metadata processor 122 includes dynamic metadatastorage 141, static metadata storage 142, metadata calculator 143,metadata determiner 144, and switch SW1.

Dynamic metadata storage 141 stores the dynamic metadata from dynamicmetadata extractor 120 at necessary timing, and also at the same timetransmits the same to terminal A of switch SW1.

Static metadata storage 142 stores the static metadata from staticmetadata extractor 117 at the same timing as dynamic metadata storage141, and also at the same time transmits the same to video informationoutputter 119. The static metadata is transmitted to video displayapparatus 102B.

Metadata calculator 143 processes the dynamic metadata stored in dynamicmetadata storage 141 and the static metadata stored in static metadatastorage 142 based on the information from metadata determiner 144, andthereby generates information in a dynamic metadata format, and thentransmits the generated dynamic metadata to terminal B of switch SW1.

Metadata determiner 144 receives the menu graphics state information(GMOF, TVPAF, MaxLLGM, and the like) from menu controller 116B and EDID(information regarding the supported video method, MAXTVLL, and thelike) from video display apparatus 102B, and controls switch SW1 basedon the information so as to select the dynamic metadata from dynamicmetadata extractor 120 (select terminal A in switch SW1), or select thedynamic metadata calculated by metadata calculator 143 (select terminalB in switch SW1) as output dynamic metadata. Also, metadata determiner144 transmits the input menu graphics state information and MAXTVLL tometadata calculator 143. Also, metadata determiner 144 performs controlso as to determine whether the metadata is stored in dynamic metadatastorage 141 and static metadata storage 142. The dynamic metadataselected and output by switch SW1 is transmitted to video displayapparatus 102B via video information outputter 119.

The criteria used by metadata determiner 144 will be described withreference to FIG. 10. In FIG. 10, when the dynamic metadata included inVSIF takes a value of “dynamic value”, dynamically changing dynamicmetadata is output. Specifically, switch SW1 is connected to terminal A(Case 1). Alternatively, switch SW1 is connected to terminal B. At thistime, metadata calculator 143 outputs information obtained by addingvalues such as GMOF, MaxLLGM, and DMBM to the input dynamic metadata toterminal B, without performing calculation on the input dynamicmetadata. As a result, dynamic metadata including GMOF, MaxLLGM, andDMBM is output (Cases 2 to 4, and Case 6).

In the case where the value of the dynamic metadata included in VSIFtakes a fixed static value, switch SW1 is connected to terminal B. Also,metadata calculator 143 calculates dynamic metadata indicating a fixedvalue by using a predetermined calculation method, and adds values suchas GMOF, MaxLLGM, and DMBM to the obtained dynamic metadata, and outputsthe dynamic metadata to which the values have been added.

In Case 3, MaxLLGM is not set in the recording medium or the HDR data asa JAVA® or HDMV command. In this case, menu controller 116B generatesMaxLLGM from the menu graphics displayed.

In Case 6 and Case 7, metadata processor 122 compares MaxLLGM andMAXTVLL. Metadata processor 122 fixes the dynamic metadata (Case 7) whenMaxLLGM is a luminance that is sufficiently higher than MAXTVLL (whenMAXTVLL is set to Low),

[2-5. Operations]

The operations of video reproduction apparatus 101B will be describedfirst. FIG. 13 is a flowchart illustrating the operations of metadataprocessor 122 included in video reproduction apparatus 101B according tothe present embodiment.

Video reproduction apparatus 101B starts reproduction of an HDR videorecorded in disc 111 or the like. GMOF is set to OFF until menu graphicsare overlaid and displayed on the video (OFF in S101). Accordingly,switch SW1 is connected to terminal A, and metadata processor 122outputs the dynamic metadata extracted by dynamic metadata extractor 120directly to video information outputter 119 (S102). Video informationoutputter 119 transmits the dynamic metadata to video display apparatus102B via HDMI or the like. Also, in the case where there is no effectiveGMOF, operations similar to those performed when GMOF is set to OFF areperformed.

When menu graphics are overlaid and displayed on the video, GMOF is setto ON (ON in S101). Accordingly, switch SW1 is connected to terminal B,and metadata processor 122 outputs the dynamic metadata output frommetadata calculator 143 to video information outputter 119.

In the case where GMOF is set to ON, and TVPAF is set to ON (ON inS103), dynamic metadata storage 141 outputs the input dynamic metadatadirectly to metadata calculator 143, without storing the input dynamicmetadata. Metadata calculator 143 adds additional metadata (GMOF,MaxLLGM, and DMBM) to the input dynamic metadata, and outputs thedynamic metadata to which the additional metadata has been added (S104).That is, metadata processor 122 substantially directly outputs thedynamic metadata extracted by dynamic metadata extractor 120.

In the case where GMOF is set to ON, and TVPAF is set to OFF or isinvalid (OFF in S103), metadata processor 122 determines whether MaxLLGMis sufficiently smaller than MAXTVLL (S105). If it is determined thatMaxLLGM is sufficiently smaller than MAXTVLL (YES in S105), as in thecase where TVPAF is set to OFF, metadata calculator 143 adds additionalmetadata (GMOF, MaxLLGM, and DMBM) to the input dynamic metadata, andoutputs the dynamic metadata to which the additional metadata has beenadded (S104). That is, metadata processor 122 substantially directlyoutputs the dynamic metadata extracted by dynamic metadata extractor120.

If it is determined that MaxLLGM is not sufficiently smaller thanMAXTVLL, or if it is determined that MAXTVLL or MaxLLGM is not present(invalid) (NO in S105), dynamic metadata storage 141 stores the inputdynamic metadata, and static metadata storage 142 stores the inputstatic metadata. Metadata calculator 143 generates fixed dynamicmetadata by using the stored static metadata and the stored dynamicmetadata, adds additional metadata (GMOF, MaxLLGM, and DMBM) to thegenerated dynamic metadata, and outputs the dynamic metadata to whichthe additional metadata has been added (S106). By video displayapparatus 102B performing processing by using the fixed dynamicmetadata, it is possible to obtain advantageous effects similar to thosewhen static metadata is used.

Specifically, for example, metadata calculator 143 keeps outputting thedynamic metadata stored in dynamic metadata storage 141 during apredetermined period, and thereby fixes the dynamic metadata during theperiod. In this case, static metadata is not used.

Alternatively, metadata calculator 143 composes the stored dynamicmetadata and the stored static metadata, and keeps outputting theobtained metadata as dynamic metadata. For example, metadata calculator143 performs a predetermined calculation (for example, averaging,weighted addition, or the like) on the video maximum luminance indicatedby the stored dynamic metadata and the video maximum luminance indicatedby the stored static metadata, and keeps outputting dynamic metadatathat indicates the obtained maximum luminance.

Alternatively, metadata calculator 143 may calculate a valuecorresponding to the static metadata as dynamic metadata. That is,metadata calculator 143 may keep outputting dynamic metadata thatindicates the maximum luminance indicated by the static metadata storedin static metadata storage 142 for a predetermined period, and therebyfix the dynamic metadata during the period. In this way, metadatacalculator 143 generates dynamic metadata that indicates the same videoluminance value (fixed value) during a predetermined period by using atleast one of the dynamic metadata stored in dynamic metadata storage 141and the static metadata stored in static metadata storage 142.

Also, when transitioning the dynamic metadata to the fixed value,metadata calculator 143 may gradually change the value of dynamicmetadata that is output from the current value to the fixed value.Alternatively, when changing the value of the dynamic metadata to beoutput from the fixed value back to the dynamic metadata extracted bydynamic metadata extractor 120, metadata calculator 143 may graduallychange the value of the dynamic metadata to be output from the fixedvalue to the current value. By doing so, it is possible to suppress arapid change in the tone mapping of video display apparatus 102B.

As used herein, to “gradually change” means that the value is changedcontinuously or stepwise during a pre-set period. That is, whentransitioning the dynamic metadata to the fixed value, the value ischanged from the current value to the fixed value via a value of 1 ormore between the current value and the fixed value during theabove-described period. Also, the term “pre-set period” refers to aperiod during which, for example, a plurality of frames are displayed.

The condition based on which it is determined that MaxLLGM issufficiently smaller than MAXTVLL may be, for example, that MaxLLGM issmaller than MAXTVLL by 50%. That is, the condition is that theproportion of MaxLLGM to MAXTVLL (MaxLLGM/MAXTVLL) is smaller than apre-set proportion (for example, 0.5).

When the proportion is small, it is possible to reduce the influence ofdynamic metadata when menu graphics are overlaid on the HDR video, buttone mapping is likely to be fixed, and thus a high-quality HDR videomay not be obtained in many cases. Accordingly, by reducing theluminance of menu graphics, the influence of dynamic tone mapping on themenu graphics is reduced such that tone mapping as dynamic as possibleis used, it is possible to display a high-quality HDR video. However,the limitation on the creation of menu graphics increases, it istherefore necessary to set the luminance to an appropriate value.

The series of processing operations are repeatedly performed until thereproduction of the video is completed (S107). For example, theprocessing operations are repeatedly performed for each frame or everyplurality of frames.

Next, the operations of video display apparatus 102B will be described.FIG. 14 is a flowchart illustrating the operations of tone mappingprocessor 134 included in video display apparatus 102B according to thepresent embodiment.

When the display of the video starts, video receiver 132 receives avideo signal and metadata. The video signal and the metadata areseparated from each other, and then transmitted separately to tonemapping processor 134.

Tone mapping processor 134 executes tone mapping according to themetadata (S112) (1) when the metadata contains static metadata, but nodynamic metadata, or (2) when dynamic metadata is present and GMOF isset to OFF or GMOF is not present. Then, the tone mapped video signal istransmitted to display 135, and display 135 displays an HDR video basedon the video signal.

Specifically, when the metadata contains static metadata, but no dynamicmetadata, tone mapping processor 134 performs static tone mappingaccording to the static metadata, or tone mapping using the result ofanalysis of the video signal.

Also, when dynamic metadata is present in the metadata, tone mappingprocessor 134 performs dynamic tone mapping according to the dynamicmetadata. In this case as well, tone mapping processor 134 may use theresult of analysis of the video signal.

When GMOF is set to ON and DMBM is set to ON or not defined (ON in S111,and ON in S113), tone mapping processor 134 performs dynamic tonemapping according to the dynamic metadata (S114). In this case as well,tone mapping processor 134 may use the result of analysis of the videosignal.

When GMOF is set to ON and DMBM is set to OFF (ON in S111, and ON inS113), tone mapping processor 134 compares MaxLLGM and MAXTVLL in thedynamic metadata (S115). If it is determined that MaxLLGM issufficiently smaller than MAXTVLL (YES in S115), tone mapping processor134 performs dynamic tone mapping according to the dynamic metadata(S114). The condition based on which it is determined that MaxLLGM issufficiently smaller than MAXTVLL is, for example, the same as that usedin step S105 described above. Also, tone mapping processor 134 may use aparameter other than MAXTVLL.

If it is determined that MaxLLGM is not sufficiently smaller thanMAXTVLL, or MaxLLGM has not been transmitted (NO in S115), tone mappingprocessor 134 performs tone mapping according to the static metadata(S116). If MaxLLGM has been transmitted, tone mapping processor 134 mayperform dynamic tone mapping according to the dynamic metadata on aluminance greater than or equal to MaxLLGM, and static tone mappingaccording to the static metadata on a luminance less than MaxLLGM.

The series of processing operations are repeatedly performed until thedisplay of the video is completed (S117). For example, the processingoperations are repeatedly performed for each frame or every plurality offrames.

As described above, tone mapping processor 134 performs a tone mappingprocess (dynamic tone mapping process) in which, by using dynamicmetadata indicating the maximum luminance of the video in each of aplurality of time intervals included in a predetermined period, theluminance of the video in each time interval is converted based onconversion characteristics according to the video maximum luminance inthe time interval. Display 135 displays the video that has undergone thetone mapping process. Metadata processor 122 generates first dynamicmetadata that indicates the maximum luminance that is constant over theplurality of time intervals by using static metadata that indicates thevideo maximum luminance during the predetermined period. Video displaysystem 100B switches between: a first operation of (i) generating firstdynamic metadata by using the static metadata, performed by metadataprocessor 122 (S106), and (ii) performing the tone mapping process byusing the first dynamic metadata, performed by tone mapping processor134 (S114); and a second operation of tone mapping processor 134performing the tone mapping process by using second dynamic metadata inwhich the maximum luminance varies over the plurality of time intervals(S112).

With this configuration, it is possible to switch between performingdynamic tone mapping and fixing tone mapping without changing theoperations of the tone mapping processor. That is, it is possible toimplement the function of fixing tone mapping without changing theconfiguration of the tone mapping processor. Also, the tone mappingprocessor may be included in the video display apparatus. Accordingly,the above-described function can be implemented simply by making achange to the video reproduction apparatus, without making any changesto the video display apparatus or while reducing the changes. It is alsopossible to suppress the occurrence of an image quality degradationcaused by the processing of the video display apparatus. As describedabove, with the method according to the present embodiment, it ispossible to improve the quality of the video displayed.

Also, video display system 100B further includes video composer 118 thatgenerates the video by overlaying graphics on the main video. Whengraphics are overlaid on the main video (ON in S101, and ON in S111),the first operation is performed (S106 and S114). When no graphics areoverlaid on the main video, the second operation or a third operation isperformed, the third operation being an operation in which the tonemapping process is performed by using the static metadata (S112). Withthis configuration, it is possible to suppress the variation in theluminance of the graphics.

Also, when graphics are overlaid on the main video (ON in S101), and theproportion of the graphics maximum luminance (MaxLLGM) relative to themaximum luminance (MAXTVLL) at which display 135 can display is higherthan a pre-set value (NO in S105), the first operation is performed(S106 and S114). When graphics are overlaid on the main video (ON inS101), and the proportion is lower than the pre-set value (YES in S105),the second operation is performed (S104 and S114).

With this configuration, in the case where the possibility of theoccurrence of a variation in the graphics luminance is high, the tonemapping is fixed. In the case where the possibility of the occurrence ofa variation in the graphics luminance is low, the dynamic tone mappingcan be continued. Accordingly, it is possible to appropriately performdynamic tone mapping while suppressing the variation in the luminance ofthe graphics.

Also, when graphics are overlaid on the main video (ON in S101), and theproportion is higher than the pre-set value (NO in S105 or No in S115),the first operation (S106 and S114) or the third operation (S116) isperformed based on the information (for example, TVPAF) associated withthe video.

This configuration allows the content creator to make a setting ofallowing or not the tone mapping processor (for example, the videodisplay apparatus) to change the tone mapping process.

Also, metadata processor 122 calculates the maximum luminance that isconstant over the plurality of time intervals and is indicated by thefirst dynamic metadata by calculating the video maximum luminanceindicated by the static metadata and the video maximum luminance in atime interval at which the first operation started, which is indicatedby the second dynamic metadata. Accordingly, it is possible to createfirst dynamic metadata that has taken into consideration of the seconddynamic metadata and the static metadata.

Also, at the time of switching from the second operation to the firstoperation, metadata processor 122 changes continuously or stepwise themaximum luminance indicated by the first dynamic metadata from themaximum luminance indicated by the second dynamic metadata to themaximum luminance that is constant over the plurality of time intervals,over a plurality of frames. With this configuration, it is possible tosmoothly change the tone mapping at the time of switching the operation.

Also, video display apparatus 102B includes tone mapping processor 134that performs a tone mapping process of, by using dynamic metadataindicating the maximum luminance of a video in each of a plurality oftime intervals included in a predetermined period, converting theluminance of the video in each time interval based on conversioncharacteristics according to the maximum luminance of the video in thetime interval, and display 135 that displays the video that hasundergone the tone mapping process. Tone mapping processor 134 switchesbetween the first operation (S114) and the second operation (S112), thefirst operation being an operation in which a tone mapping process isperformed by using first dynamic metadata that is generated by usingstatic metadata indicating the maximum luminance of the video during apredetermined period and indicates the maximum luminance that isconstant over the plurality of time intervals, and the second operationbeing an operation in which a tone mapping process is performed by usingsecond dynamic metadata in which the maximum luminance varies over theplurality of time intervals.

With this configuration, it is possible to switch between performingdynamic tone mapping and fixing tone mapping without changing theoperations of the tone mapping processor. That is, it is possible toimplement the function of fixing tone mapping without changing theconfiguration of the tone mapping processor. Also, it is possible topossible to suppress the occurrence of an image quality degradationcaused by the processing of the video display apparatus. As describedabove, with the method according to the present embodiment, it ispossible to improve the quality of the video displayed.

Also, tone mapping processor 134 performs the first operation when thevideo contains graphics (ON in S111) (S114), and performs the secondoperation or a third operation of performing the tone mapping process byusing the static metadata (S112) when the video contains no graphics(OFF in S111).

Also, when the video contains graphics (ON in S111), and tone mappingprocessor 134 is forced to perform the first tone mapping process (ON inS113) by a flag (DMBM) that forces tone mapping processor 134 to performthe first tone mapping process using dynamic metadata among the firsttone mapping process and the second tone mapping process using staticmetadata, tone mapping processor 134 performs the first tone mappingprocess. When tone mapping processor 134 is not forced to perform thefirst tone mapping process by the flag (DMBM) (OFF in S113), tonemapping processor 134 performs the first tone mapping process (S114) orthe second tone mapping process (S116). When the first operation isperformed (S106 and S114), tone mapping processor 134 is forced toperform the first tone mapping process by the flag (DMBM).

With this configuration, it is possible to cause the video reproductionapparatus to forcibly perform processing using the first dynamicmetadata, and thus tone mapping fixing processing can be reliablyimplemented by using the first dynamic metadata.

Also, when the video contains graphics and tone mapping processor 134 isnot forced to perform the first tone mapping process by the flag (DMBM)(ON in S111 and OFF in S113), and when the proportion of the graphicsmaximum luminance (MaxLLGM) relative to the maximum luminance (MAXTVLL)at which display 135 can display is higher than a pre-set value (NO inS115), tone mapping processor 134 performs the second tone mappingprocess (S116). When the proportion is lower than the pre-set value (YESin S115), tone mapping processor 134 performs the first tone mappingprocess (S114).

With this configuration, in the case where the possibility of theoccurrence of a variation in the graphics luminance is high, the tonemapping is fixed. In the case where the possibility of the occurrence ofa variation in the graphics luminance is low, the dynamic tone mappingcan be continued. Accordingly, it is possible to appropriately performdynamic tone mapping while suppressing the variation in the luminance ofthe graphics.

[3. Variation]

The HDR video reproduced by the video reproduction apparatus may be avideo included in, for example, a Blu-ray disc, a DVD, a moving imagedelivery site on the Internet, broadcast, or a HDD (Hard Disk Drive).

The video reproduction apparatus described above may be an apparatusthat decodes a compressed video signal transmitted from a recordingmedium, a broadcast, or the Internet, and transmits the decoded videosignal to a video display apparatus. Examples of the video reproductionapparatus include a disc player, a disc recorder, a set top box, atelevision set, a personal computer, and a smartphone. Also, videodisplay apparatus 102B may have some or all of the functions of videoreproduction apparatus 101B. For example, among the processors includedin video reproduction apparatus 101B, video display apparatus 102B mayinclude the processors other than disc 111 and BD-ROM driver 112. Also,video receiver 132, metadata acquirer 133, and tone mapping processor134 included in video display apparatus 102B may be incorporated invideo reproduction apparatus 101B. Also, video reproduction apparatus101B may have some of the functions of tone mapping processor 134.

The video signal transmitting means that transmits the video signal fromthe video reproduction apparatus to the video display apparatus may be ameans that transmits the video signal in an uncompressed state such asHDMI, DVI, or DP, or may be a means that transmits the video signal in acompressed form such as transmission via a network.

The maximum luminance information or the tone mapping information of thevideo display apparatus can be set in the video reproduction apparatusby a user inputting the information into the video reproductionapparatus via a remote controller or the like, or via an operatingapparatus included in the video reproduction apparatus. Alternatively,the user may acquire these information via the Internet or any othermeans, store the acquired information in a portable storage medium, andtransmit the information to the video reproduction apparatus via theportable storage medium. Alternatively, the video reproduction apparatusmay be connected directly to the Internet such that the videoreproduction apparatus can acquire these information from a database ona server. Furthermore, the video reproduction apparatus may display atest pattern on the video display apparatus such that these informationcan be acquired or stored, with the user confirming the characteristicsof the video display apparatus by using the displayed test pattern.

The video reproduction apparatus may generate graphics luminanceinformation (MaxLLGM) by detecting the luminance of graphics (subtitlesor a menu) from the data, or acquire the luminance of graphics createdin advance during production of the video data. For example, thegraphics luminance may be recorded in a disc, or may be transmitted asmetadata via broadcasting or the Internet. The video reproductionapparatus reads the graphics luminance, and transmits the read graphicsluminance to the video display apparatus as a portion of the dynamicmetadata. Alternatively, the luminance information of graphics(subtitles or a menu) may be recorded in a database on a server that isconnected to the Internet as information regarding the content to bereproduced such that the video reproduction apparatus can acquire thegraphics luminance information (MaxLLGM) from the database, and transmitthe acquired graphics luminance information to the video displayapparatus.

The proportion (for example, 50%) used to compare MaxLLGM and MAXTVLLmay be determined according to the feature of the video signal based onwhich the video is to be displayed, and be stored in a disc.Alternatively, the proportion may be determined according to the featureof the video display apparatus. Alternatively, the proportion may beacquired from a database on the Internet.

Up to here, the video display system according to the embodiment of thepresent disclosure has been described, but the present disclosure is notlimited to the embodiment.

Also, the processors included in the video display system according tothe embodiment described above are typically implemented as LSIs, whichare integrated circuits. They may be individual single chips, or a partor all of them may be configured in a single chip.

Also, implementation of an integrated circuit is not limited to an LSI,and may be implemented by a dedicated circuit or a general-purposeprocessor. It is also possible to use an FPGA (Field Programmable GateArray) that can be programmed after LSI production or a reconfigurableprocessor that enables reconfiguration of the connection and setting ofcircuit cells in the LSI.

Also, in the embodiment described above, the structural elements may beconfigured using dedicated hardware, or may be implemented by executinga software program suitable for the structural elements. The structuralelements may be implemented by a program executor such as a CPU or aprocessor reading and executing a software program recorded in arecording medium such as a hard disk or a semiconductor memory.

Also, the present disclosure may be implemented as a method executed bythe video display system.

Also, the functional blocks shown in the block diagrams are merelyexamples. Accordingly, it is possible to implement a plurality offunctional blocks as a single functional block, or divide a singlefunctional block into a plurality of blocks. Alternatively, somefunctions may be transferred to other functional blocks. Also, thefunctions of a plurality of functional blocks that have similarfunctions may be processed by a single piece of hardware or software inparallel or by time division.

Also, the order in which the steps of each flowchart are performed ismerely an example provided to specifically describe the presentdisclosure. Accordingly, the order is not limited to that describedabove. Also, one or more of the steps described above may be performedsimultaneously with (in parallel to) other steps.

A video display system according to one or more aspects has beendescribed by way of embodiments above, but the present disclosure is notlimited to the embodiments given above. Embodiments obtained by makingvarious modifications that can be conceived by a person having ordinaryskill in the art to the above embodiments as well as embodimentsimplemented by any combination of the structural elements of differentembodiments without departing from the gist of the present disclosuremay also be encompassed within the scope of one or more aspects.

INDUSTRIAL APPLICABILITY

The present disclosure is applicable to a video display system, a videoreproduction apparatus, or a video display apparatus.

REFERENCE MARKS IN THE DRAWINGS

-   -   100, 100A, 100B video display system    -   101, 101A, 101B video reproduction apparatus    -   102, 102A, 102B video display apparatus    -   111 disc    -   112 BD-ROM driver    -   113 demultiplexer    -   114 PG decoder    -   115 video decoder    -   116, 116B menu controller    -   117 static metadata extractor    -   118 video composer    -   119 video information outputter    -   120 dynamic metadata extractor    -   121 metadata switch    -   122 metadata processor    -   131 luminance information storage    -   132 video receiver    -   133 metadata acquirer    -   134 tone mapping processor    -   135 display    -   141 dynamic metadata storage    -   142 static metadata storage    -   143 metadata calculator    -   144 metadata determiner

The invention claimed is:
 1. A video display system, comprising: a tone mapping processor that performs a tone mapping process of, by using dynamic metadata indicating a maximum luminance of a video in each of a plurality of time intervals included in a predetermined period, converting a luminance of the video in each time interval based on conversion characteristics according to the maximum luminance of the video in the time interval; a display that displays the video that has undergone the tone mapping process; a metadata processor that generates first dynamic metadata that indicates the maximum luminance that is constant over the plurality of time intervals by using static metadata that indicates a maximum luminance of the video in the predetermined period, and a composer that generates the video by overlaying graphics on a main video, wherein: the video display system switches between: a first operation of (i) generating the first dynamic metadata by using the static metadata, performed by the metadata processor, and (ii) performing the tone mapping process by using the first dynamic metadata, performed by the tone mapping processor; and a second operation of performing the tone mapping process by using second dynamic metadata in which the maximum luminance varies over the plurality of time intervals, performed by the tone mapping processor, when the graphics are overlaid on the main video, and a proportion of a maximum luminance of the graphics relative to a maximum luminance at which the display can display is higher than a pre-set value, the first operation is performed, and when the graphics are not overlaid on the main video, the second operation or a third operation of performing the tone mapping process by using the static metadata is performed, and when the graphics are overlaid on the main video, and the proportion is lower than the pre-set value, the second operation is performed.
 2. The video display system according to claim 1, wherein, when the graphics are overlaid on the main video, and the proportion is higher than the pre-set value, the first operation or the third operation is performed based on information associated with the video.
 3. The video display system according to claim 1, wherein the metadata processor calculates the maximum luminance that is constant over the plurality of time intervals and is indicated by the first dynamic metadata by calculating the maximum luminance of the video indicated by the static metadata and a maximum luminance of the video in a time interval at which the first operation started, which is indicated by the second dynamic metadata.
 4. The video display system according to claim 1, wherein, at a time of switching from the second operation to the first operation, the metadata processor changes continuously or stepwise the maximum luminance indicated by the first dynamic metadata from the maximum luminance indicated by the second dynamic metadata to the maximum luminance that is constant over the plurality of time intervals, over a plurality of frames.
 5. A video display method in a video display system, the video display method comprising: performing a tone mapping process of, by using dynamic metadata indicating a maximum luminance of a video in each of a plurality of time intervals included in a predetermined period, converting a luminance of the video in each time interval based on conversion characteristics according to the maximum luminance of the video in the time interval; displaying the video that has undergone the tone mapping process step; generating first dynamic metadata that indicates the maximum luminance that is constant over the plurality of time intervals by using static metadata that indicates a maximum luminance of the video in the predetermined period; and generating the video by overlaying graphics on a main video, wherein: switching is performed between: a first operation of (i) generating the first dynamic metadata by using the static metadata, and (ii) performing the tone mapping process by using the first dynamic metadata; and a second operation of performing the tone mapping process by using second dynamic metadata in which the maximum luminance varies over the plurality of time intervals, when the graphics are overlaid on the main video, and a proportion of a maximum luminance of the graphics relative to a maximum luminance at which the display can display is higher than a pre-set value, the first operation is performed, and when the graphics are not overlaid on the main video, the second operation or a third operation of performing the tone mapping process by using the static metadata is performed, and when the graphics are overlaid on the main video, and the proportion is lower than the pre-set value, the second operation is performed.
 6. The video display method according to claim 5, wherein, when the graphics are overlaid on the main video, and the proportion is higher than the pre-set value, the first operation or the third operation is performed based on information associated with the video.
 7. The video display method according to claim 5, wherein the maximum luminance that is constant over the plurality of time intervals and is indicated by the first dynamic metadata is calculated by calculating the maximum luminance of the video indicated by the static metadata and a maximum luminance of the video in a time interval at which the first operation started, which is indicated by the second dynamic metadata.
 8. The video display method according to claim 5, wherein, at a time of switching from the second operation to the first operation, the maximum luminance indicated by the first dynamic metadata is changed continuously or stepwise from the maximum luminance indicated by the second dynamic metadata to the maximum luminance that is constant over the plurality of time intervals, over a plurality of frames. 